src/base64.c

   1 /*
   2  * base64.c -- base-64 conversion routines.
   3  *
   4  * For license terms, see the file COPYING in this directory.
   5  *
   6  * This base 64 encoding is defined in RFC2045 section 6.8,
   7  * "Base64 Content-Transfer-Encoding", but lines must not be broken in the
   8  * scheme used here.
   9  *
  10  * Modified by Hiroyuki Yamamoto <hiro-y@kcn.ne.jp>
  11  */
  12
  13 #include "defs.h"
  14
  15 #include <ctype.h>
  16 #include <string.h>
  17 #include <glib.h>
  18
  19 #include "base64.h"
  20
  21 static const char base64digits[] =
  22    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  23
  24 #define BAD     -1
  25 static const char base64val[] = {
  26     BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD,
  27     BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD,
  28     BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD, 62, BAD,BAD,BAD, 63,
  29      52, 53, 54, 55,  56, 57, 58, 59,  60, 61,BAD,BAD, BAD,BAD,BAD,BAD,
  30     BAD,  0,  1,  2,   3,  4,  5,  6,   7,  8,  9, 10,  11, 12, 13, 14,
  31      15, 16, 17, 18,  19, 20, 21, 22,  23, 24, 25,BAD, BAD,BAD,BAD,BAD,
  32     BAD, 26, 27, 28,  29, 30, 31, 32,  33, 34, 35, 36,  37, 38, 39, 40,
  33      41, 42, 43, 44,  45, 46, 47, 48,  49, 50, 51,BAD, BAD,BAD,BAD,BAD
  34 };
  35 #define DECODE64(c)  (isascii(c) ? base64val[c] : BAD)
  36
  37 void to64frombits(unsigned char *out, const unsigned char *in, int inlen)
  38 /* raw bytes in quasi-big-endian order to base 64 string (NUL-terminated) */
  39 {
  40     for (; inlen >= 3; inlen -= 3)
  41     {
  42         *out++ = base64digits[in[0] >> 2];
  43         *out++ = base64digits[((in[0] << 4) & 0x30) | (in[1] >> 4)];
  44         *out++ = base64digits[((in[1] << 2) & 0x3c) | (in[2] >> 6)];
  45         *out++ = base64digits[in[2] & 0x3f];
  46         in += 3;
  47     }
  48     if (inlen > 0)
  49     {
  50         unsigned char fragment;
  51
  52         *out++ = base64digits[in[0] >> 2];
  53         fragment = (in[0] << 4) & 0x30;
  54         if (inlen > 1)
  55             fragment |= in[1] >> 4;
  56         *out++ = base64digits[fragment];
  57         *out++ = (inlen < 2) ? '=' : base64digits[(in[1] << 2) & 0x3c];
  58         *out++ = '=';
  59     }
  60     *out = '\0';
  61 }
  62
  63 int from64tobits(char *out, const char *in)
  64 /* base 64 to raw bytes in quasi-big-endian order, returning count of bytes */
  65 {
  66     int len = 0;
  67     register unsigned char digit1, digit2, digit3, digit4;
  68
  69     if (in[0] == '+' && in[1] == ' ')
  70         in += 2;
  71     if (*in == '\r' || *in == '\n')
  72         return 0;
  73
  74     do {
  75         digit1 = in[0];
  76         if (DECODE64(digit1) == BAD)
  77             return -1;
  78         digit2 = in[1];
  79         if (DECODE64(digit2) == BAD)
  80             return -1;
  81         digit3 = in[2];
  82         if (digit3 != '=' && DECODE64(digit3) == BAD)
  83             return -1;
  84         digit4 = in[3];
  85         if (digit4 != '=' && DECODE64(digit4) == BAD)
  86             return -1;
  87         in += 4;
  88         *out++ = (DECODE64(digit1) << 2) | ((DECODE64(digit2) >> 4) & 0x03);
  89         ++len;
  90         if (digit3 != '=')
  91         {
  92             *out++ = ((DECODE64(digit2) << 4) & 0xf0) | (DECODE64(digit3) >> 2);
  93             ++len;
  94             if (digit4 != '=')
  95             {
  96                 *out++ = ((DECODE64(digit3) << 6) & 0xc0) | DECODE64(digit4);
  97                 ++len;
  98             }
  99         }
 100     } while (*in && *in != '\r' && *in != '\n' && digit4 != '=');
 101
 102     return len;
 103 }
 104
 105 struct _Base64Decoder
 106 {
 107         int buf_len;
 108         unsigned char buf[4];
 109 };
 110
 111 Base64Decoder *
 112 base64_decoder_new (void)
 113 {
 114         Base64Decoder *decoder;
 115
 116         decoder = g_new0 (Base64Decoder, 1);
 117         return decoder;
 118 }
 119
 120 void
 121 base64_decoder_free (Base64Decoder *decoder)
 122 {
 123         g_free (decoder);
 124 }
 125
 126 int
 127 base64_decoder_decode (Base64Decoder *decoder,
 128                        const char    *in,
 129                        char          *out)
 130 {
 131         int len = 0;
 132         int buf_len;
 133         unsigned char buf[4];
 134
 135         g_return_val_if_fail (decoder != NULL, -1);
 136         g_return_val_if_fail (in != NULL, -1);
 137         g_return_val_if_fail (out != NULL, -1);
 138
 139         buf_len = decoder->buf_len;
 140         memcpy (buf, decoder->buf, sizeof(buf));
 141         while (1) {
 142                 while (buf_len < 4) {
 143                         int c = *(unsigned char *)in++;
 144                         if (c == '\0') break;
 145                         if (c == '\r' || c == '\n') continue;
 146                         if (c != '=' && DECODE64(c) == BAD)
 147                                 return -1;
 148                         buf[buf_len++] = c;
 149                 }
 150                 if (buf_len < 4 || buf[0] == '=' || buf[1] == '=') {
 151                         decoder->buf_len = buf_len;
 152                         memcpy (decoder->buf, buf, sizeof(buf));
 153                         return len;
 154                 }
 155                 *out++ = ((DECODE64(buf[0]) << 2)
 156                           | ((DECODE64(buf[1]) >> 4) & 0x03));
 157                 ++len;
 158                 if (buf[2] != '=') {
 159                         *out++ = (((DECODE64(buf[1]) << 4) & 0xf0)
 160                                   | (DECODE64(buf[2]) >> 2));
 161                         ++len;
 162                         if (buf[3] != '=') {
 163                                 *out++ = (((DECODE64(buf[2]) << 6) & 0xc0)
 164                                           | DECODE64(buf[3]));
 165                                 ++len;
 166                         }
 167                 }
 168                 buf_len = 0;
 169                 if (buf[2] == '=' || buf[3] == '=') {
 170                         decoder->buf_len = 0;
 171                         return len;
 172                 }
 173         }
 174 }
 175
 176 /* base64.c ends here */